I would add the mini pcie slot, and move "Easy to add a WiFi card" under that.
Reasons I like the Galileo are everything Clay said, plus I like that it is a 486 processor,
lots of memory, and an Arduino compatible pin-out for use of Arduino shields.
I would not consider running less than a pretty complete Linux build plus a build tool chain.
I don't know what mips this processor is rated at - but it does superbly with every build and task I have thrown at it.
Ruby on Rails makes it a very competent little web server.
And this is the kind of stuff I enjoy doing...
As far as I know, the Galileo is the only maker-friendly SBC that has real WiFi support thanks to PCIe. That's a huge asset. On top of that, once you have a good bitbake environment set up, making custom kernels for it is a snap, and very satisfying to play around with.
I think the Galileo is a poor fit for an Arduino platform, but it excels as a competitor to the Raspberry Pi / BeagleBone because of it's strong hardware, x86-ness, and real WiFi support.
I don't think that the Galileo is even close to be a competitor to a rPi/BBB, simply due to the fact that it does not have any true video output/USB input options like those boards have.
Perhaps I should have clarified: The Galileo will never be an HTPC, but for headless/embedded applications, it's very very cool. Also, it does have USB input.
I have a Raspberry Pi as well. I consider the hdmi output and risc processor to be two of it's negatives... Not wanting to build a kiosk with a cheap terminal and keyboard, I find the Galileo to be much more capable for my needs.
What's wrong with having video output via HDMI? Pretty much each and every TV and computer monitor has such connection these days...
And why is the ARM/RISC processor a negative?
I have six monitors currently, hooked up to various PCs in my home. Very last thing I need is another monitor with HDMI input dedicated to an embedded processor. RISC is a negative because of the name - the instruction set is reduced, which means the registers are smaller and it takes more instructions to get anything done. My favorite processors were in the Motorola family. The 68000 was an elegant instruction set. Intel is not bad though, once you get past the page tables. Maybe more important, Intel is a viable company.
I think you really need to read up about what RISC really means. Reduced by no means results in reduced performance. And where do you get the nonsense that "registers are smaller"? As a matter of fact, all RISC processors have loads more of available registers, and most instructions of a RISC processor are handled in a single cycle, while CISC processor like the x86 design will take multiple cycles. That in almost all cases levels the "more instructions to get anything done". Not to mention that the most common RISC instruction sets are "compiler optimized", so it doesn't really matter how many instructions on the CPU a certain tasks takes...